A system for using heat pipes and a deep well drilled in the ground as a heat sink for air conditioning systems without a compressor.
The invention was disclosed in Disclosure Document No. 461662, entitled Earth Cooling, received by the Patent Office on Aug. 31, 1999, and listing Samuel J. Raff as inventor. Peak electricity load during the summer is due to the use of air conditioning. In conventional air conditioners, the main energy consumer is the compressor. This increases the pressure and temperature of the gaseous working fluid (usually freon) enough so that if the compressed gas is cooled (by a heat sink) to within a few degrees of room temperature, it will condense into a liquid. It is the subsequent evaporation of this liquid which further cools the coils to below 60xc2x0 F. so that the air flowing over them is adequately cold that it can cool the living spaces. Notice that the heat sink need not be below room temperature, and in fact, most common home air conditioners cool the compressed gas using outside air in a heat exchanger.
Several prior art devices have utilized the earth as a source of heat and as a heat sink. One example is a geothermal heat pump having the working fluid from the heat pump flow through tubes that are buried several feet below the ground. The heat pump can act as either a heater or an air conditioner; therefore, the fluid flowing through the pipes uses the surrounding earth as both a heat source and heat sink.
U.S. Pat. No. 5,738,164 (Hildebrand) discloses such a system for energy exchange between the earth and an energy exchanger 4. The disclosed device affects energy exchange between earth soil and an energy exchanger. The device includes a soil heat exchanger 25, and supply and return flow conduits for connecting the soil exchanger with the energy exchanger. The soil heat exchanger includes a thermoinsulated supply pipe arranged in a bore well formed in the ground, a pump provided at the end of the flow duct 27 and a shroud pipe 34 surrounding the flow duct and the pump. Lateral inlet openings 46 and a return flow pipe 40 complete the system. A section of the shroud pipe 34 functions as a thermopipe and the system can reach a depth of 800 meters. A thermopile is a thermal insulated section formed with a correspondingly bigger wall thickness.
U.S. Pat. No. 3,195,619 (Tippmann) discloses a heat transfer method for precluding the formation of ice on pavement. Heat pipes transfer heat to the pavement from the natural heat of the earth below the frost level. A lower end of the vessel contains a measured amount of a volatile substance, such as ammonia, convertible to a liquid state at low temperature at approximately 30xc2x0 F. and to a gaseous state at higher temperatures, depending upon the pressure.
U.S. Pat. No. 5,533,355 (Rawlings) discloses a ground source heat pump system with subterranean piping insulation and a modular heat exchanger.
The prior art does not disclose a system for using the ground as a heat sink without a compressor as in the present invention. Such a system must require that the ground temperature remain below or close to 60xc2x0 F. The normal deep ground temperature in the vicinity of the major population dense areas of Boston, New York, Philadelphia, Washington, D.C. and Richmond on the east coast of the United States is below 57xc2x0 F., but it will not remain that low after a season of being used as a heat sink. However, in all these population dense areas, as well as many others in the world, the winters are cold. This provides an opportunity to cool the ground during the winter so that it may be used as a heat sink again in the next air conditioning season.
It is an object of the invention to provide a system that provides cool water for an air conditioning system relying upon the earth as a heat sink.
It is another object of the invention to provide a system using the earth as a heat sink that is inexpensive to build and operate.
It is another object of the invention to provide a cooling system using the earth as a heat sink that is reliable in its operation.
It is another object of the invention to provide a system using the earth as heat sink that removes accumulated heat during winter months.
It is another object of the invention to provide an air conditioning system that uses a minimum amount of electricity to reduce peak electricity use during the summer.
These and other objects of the invention will become apparent to one of ordinary skill in the art after reviewing the disclosure of the invention.
The system uses a well drilled into the ground and filled with water. The well is encased and sealed at its bottom to prevent excessive loss of water. The casing of the well is in contact with the surrounding earth for heat conduction. A pipe is placed within the well with a pump at its distal end. The pump draws cold water from within the well into the pipe, out of the well into a heat exchanger which is preferable in the air flow of the house heating system. After the water has gone through the heat exchanger, it is returned to the well. A float operated valve of conventional type, not shown in the drawing, can be used to automatically add water to the well.
Heat pipes like those described by Trippman are used to dissipate, in winter, the heat accumulated in the ground during the summer cooling months. They extend outwardly and upward from the water near the top of the well and contain a substance that will absorb heat and evaporate at the end in the well and condense and release heat at the opposite end. An upward slant of the heat pipe ensures that this heat transfer occurs only in the direction away from the well. These heat pipes cool the water in the well which in turn, cools the ground by conduction. The heat flows from the ground into the well in the reverse of how it flowed in the summer. Two things about this are notable. First the heat pipes are unidirectional. They can only carry heat up and out of the well, never in the reverse direction. Second, they are completely passive so that no electric energy is consumed by the system in the winter. If they are in the ground (under a lawn for example) they should be buried at a depth of about three feet. However, they may also be under a paved area or even on a roof.
Also, for the well, the main thermal flow resistance in the ground is in the immediate vicinity of the well. Therefore, a deeper well, or a well of larger diameter, will make the system more effective. It is also noteworthy that, although the system described here is intended for a detached one family home, by increasing the well depth and possibly its diameter, a similar system can be effective for a block of attached homes, an apartment complex and even an office complex or larger building. The system operates well in regions where air conditioning is required in the summer but the winters are cold.